System and method for adjusting light intensity in a display system

ABSTRACT

A display system includes a backlight configured to project light including a housing and one or more light emitting elements received in the housing and one or more reflective portions disposed on the housing. A first display unit is disposed proximate the backlight includes a liquid crystal layer and at least one reflective polarizer. A second display unit is disposed proximate the first display unit. The second display unit includes a TFT display layer and at least one linear polarizer. At least one microcontroller is in communication with one or more of the backlight, the first display unit and the second display unit. The at least one microcontroller executes instructions to adjust the liquid crystal layer of the first display unit between a first transmissive state and a second transmissive state.

TECHNICAL FIELD

The present disclosure generally relates to systems and methods foradjusting light intensity in a display system, and more particularly tosystems and methods for improving the optical efficiency of the displaysystem using a reflective polarizing arrangement.

BACKGROUND

Electronic displays are provided in many contexts to electronicallyrender digital information to a viewer. The electronic displays receiveinformation and render the information through lighted cells in patternsthat reflect the texts and pictures employed to convey the information.

An exemplary prior art electronic display is illustrated in FIG. 1. Theelectronic display 1 is employed to providing electronic content to aviewer of the electronic display. The display 1 includes a bezel 2defining a border of the display screen. Defining the portion within thebezel 2 is a display portion. The display portion includes a backlitdisplay 3 cooperating with a plurality of LEDs (not shown) and a displaylinear polarizer 4.

The display 1 is provided with a first layer 5. This first layer 5 is aneutral density filter that reduces or modifies the intensity of allwavelengths or colors, of light equally. The filter transmission mayrange from colorless (clear) to grey (opaque) with a constanttransmission rate. An anti-reflective film 6 is disposed on the firstlayer 5 and may cancel light reflections to minimize a viewer fromseeing visibility variations from the electronic display 1 due to thelighting environment in which the electronic display 1 is exposed.

Exemplary prior art electronic displays may control dimming and adjustvisual properties of the display by creating and controlling zones ofLEDs to adjust backlighting. However, calibrating and controlling theLED zones can be complex and fail to provide the contrast leveladjustments sought in the display.

SUMMARY

Systems and methods are disclosed herein for enhancing the visibility oflight-based information rendered on a display system utilizing a localdimming technique. The display system includes a backlight including ahousing receiving one or more light emitting elements to generate andproject light from the backlight and one or more reflective portionsdisposed on the housing. A first display unit is disposed proximate thebacklight and includes an upper substrate, a liquid crystal layercooperating with the upper substrate of the first display unit and alower substrate disposed opposite the upper substrate of the firstdisplay unit that cooperates with the liquid crystal layer. At least onereflective polarizer cooperates with one or more of the upper substrateof the first display unit and the lower substrate of the first displayunit.

A second display unit is disposed proximate the first display unit. Thesecond display unit includes an upper substrate, a thin-film transistor(TFT) display layer cooperating with the upper substrate of the seconddisplay unit and a lower substrate disposed opposite the upper substrateof the second display unit that cooperates with the TFT display layer.At least one linear polarizer cooperates with one or more of the uppersubstrate of the second display unit and the lower substrate of thesecond display unit.

At least one microcontroller is in communication with one or more of thebacklight, the first display unit and the second display unit. The atleast one microcontroller executes instructions to adjust the liquidcrystal layer of the first display unit between a first transmissivestate and a second transmissive state.

A diffusing element is disposed proximate an upper surface of thehousing, wherein the diffusing element cooperates with the backlight todistribute light generated by the one or more light emitting elements orreflected from the one or more reflective portions of the backlight. Theat least one reflective polarizer of the first display unit may includea first reflective polarizer having a body including an upper surfaceand an opposing lower surface that cooperates with the upper substrateof the first display unit and a second reflective polarizer having abody including an upper surface cooperating with the lower substrate ofthe first display unit and an opposing lower surface.

A brightness enhancing film cooperates with the lower surface of thesecond reflective polarizer. The liquid crystal layer of the firstdisplay unit includes a thin film transistor liquid crystal display(LCD) that is disposed between and cooperates with the upper substrateof the first display unit and the lower substrate of the first displayunit.

The at least one linear polarizer of the second display unit includes afirst linear polarizer having a body including an upper surfacecooperating with the lower substrate of the second display unit and anopposing lower surface and a second linear polarizer having a bodyincluding an upper surface and an opposing lower surface cooperatingwith the upper substrate of the second display unit. The TFT displaylayer of the second display unit may include a thin film transistorliquid crystal display disposed between and cooperating with the uppersubstrate of the second display unit and opposing lower substrate of thesecond display unit.

A diffuser may be disposed between the first display unit and the seconddisplay unit. The diffuser provides a light profile transition for lighttransmitted through the first display unit.

The above features and advantages and other features and advantages ofthe present teachings are readily apparent from the following detaileddescription for carrying out the teachings when taken in connection withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an exemplary prior art implementation of anelectronic display.

FIG. 2 is a schematic illustration of a system for adjusting lightintensity for a display system in accordance with one or more of theembodiments disclosed herein.

FIG. 3 is a schematic side view of the display system constructed inaccordance with one or more of the embodiments disclosed herein.

FIG. 4 is a schematic side view of the display system constructed inaccordance with an alternative embodiment disclosed herein.

FIG. 5 is a schematic side view of the display system illustratingprojection of light through the one or more reflective polarizers inconnection with one dimming mode of the display constructed inaccordance with one or more of the embodiments disclosed herein.

FIG. 6 is a schematic side view of the display system illustratingprojection of light through the one or more reflective polarizers inconnection with another dimming mode of the display constructed inaccordance with one or more of the embodiments disclosed herein.

FIG. 7 is a flow chart illustrating a method for adjusting lightintensity of the display system in accordance with one or moreembodiments disclosed herein.

FIG. 8 is a schematic side view of the display system illustratingprojection of light through the one or more reflective polarizers inconnection with yet another dimming mode of the display constructed inaccordance with one or more of the embodiments disclosed herein.

The present disclosure may have various modifications and alternativeforms, and some representative embodiments are shown by way of examplein the drawings and will be described in detail herein. Novel aspects ofthis disclosure are not limited to the particular forms illustrated inthe above-enumerated drawings. Rather, the disclosure is to covermodifications, equivalents, and combinations falling within the scope ofthe disclosure as encompassed by the appended claims.

DETAILED DESCRIPTION

Those having ordinary skill in the art will recognize that terms such as“above,” “below,” “front”, “back”, “upward,” “downward,” “top,”“bottom,” etc., may be used descriptively herein without representinglimitations on the scope of the disclosure, as defined by the appendedclaims. Furthermore, the present teachings may be described in terms offunctional and/or logical block components and/or various processingsteps. Such block components may be comprised of various hardware,software, and/or firmware components configured to perform the specifiedfunctions.

Referring to the Figures, wherein like numerals indicate like partsthroughout the several views, a display system 10 is generallydescribed. The display system 10 is not shown or described as part of aspecific application. However, it should be appreciated that the displaysystem 10, or embodiments thereof, may be utilized in many differentapplications, such as but not limited to a vehicular application, anentertainment application, and an advertising display application.

Exemplary vehicular applications include but are not limited toautomobiles, airplanes, trains, boats, motorcycles, all-terrain vehicles(ATV), utility task vehicles (UTV), etc. For example, the display system10 may be incorporated into an instrument cluster, a center consoledisplay, a passenger entertainment display, etc. Exemplary entertainmentapplications include, but are not limited to, gaming systems,televisions, computer screens, etc. The teachings of this disclosure arenot limited to the exemplary applications and environments noted above.

Referring now to FIG. 2, the display system 10 may include one or morecomponents in electrical communication with at least one microcontroller12. The components of the display system 10 may be coupled to the atleast one microcontroller in a wired or wireless manner. The at leastone microcontroller 12 may include one or more processors (P), each ofwhich may be embodied as a separate processor, an application specificintegrated circuit (ASIC), or a dedicated electronic control unit.

The at least one microcontroller 12 may be any sort of electronicprocessor (implemented in hardware, software, or a combination of both).The at least one microcontroller 12 also includes tangible,non-transitory memory (M), e.g., read only memory in the form ofoptical, magnetic, and/or flash memory. For example, the at least onemicrocontroller 12 may include application-suitable amounts ofrandom-access memory, read-only memory, flash memory and other types ofelectrically-erasable programmable read-only memory, as well asaccompanying hardware in the form of a high-speed clock or timer,analog-to-digital and digital-to-analog circuitry, and input/outputcircuitry and devices, as well as appropriate signal conditioning andbuffer circuitry.

Computer-readable and executable instructions embodying the presentmethod may be stored in memory (M) and executed as set forth herein. Theexecutable instructions may be a series of instructions employed to runapplications on the at least one microcontroller 12 (either in theforeground or background). The at least one microcontroller 12 mayreceive commands and information, in the form of one or more inputsignals, generally represented by box and numeral 14, from variouscontrols or components in the vehicle (not shown) and communicateinstructions to the display 10 through one or more control signals 16 tocontrol the display 10.

The one or more control signals 16 may represent a dimming level valueor command received from one or more sources. Non-limiting examples ofthe one or more sources may include an ambient light sensor or othervehicle component control signal, or a signal from a user actuatingdevice. The actuating may be an engageable input device or any sort oftouch screen interface. The actuating device is not limited to touchableinterfaces, and thus, any known human machine interface (HMI) techniquemay be implemented along with actuating device. The actuating device maybe implemented by a user to request a light permeability or dimminglevel for the display system 10.

Referring now to FIGS. 3-6, one or more embodiments of a display system10 are schematically displayed and described in greater detail herein.The display system 10 may include at least one light source or backlight20 including one or more light emitting elements 22. The one or morelight emitting elements 22 may include one or more light emitting diodes(LEDs) that generate and project light from the backlight to one or morecomponents of the display system 10.

In one or more embodiments, the one or more light emitting elements 22may be arranged in the backlight 20 in a direct-type LED arrangement orin an edge-type LED arrangement. The direct-type LED arrangementpositions the one or more LEDs in an array in alignment with the one ormore components of the display system to provide direct lighting for thedisplay system 10.

The edge-type LED arrangement positions the one or more light emittingelements 22 around a perimeter of the backlight 20. The edge-type LEDarrangement may include one or more reflective plates that directs lightfrom the one or more LEDs toward the one or more components of thedisplay system 10.

The backlight 20 and one or more light emitting elements 22 areadjustable between at least an off state and an on state to illuminateone or more components of the display 10. In one or more embodiments,when the backlight 20 is placed in the off state, the backlight does notemit light and corresponds to zero percent (0%) light transmittance orlight intensity. When the backlight is placed in an on state, the one ormore light emitting elements 22 of the backlight 20 emit lightcorresponding to a range of light transmittance or light intensitybetween greater than zero percent (0%) and one hundred percent (100%)light transmittance or light intensity. The light intensity of the oneor more light elements 22 of the backlight 20 may be controlled by theat least one microcontroller 12.

The backlight 20 may include a housing 24 defining at least an uppersurface 26 and an opposing lower surface 28. The housing 24 may beconfigured to receive or cooperate with the one or more light emittingelements 22. The upper surface 26 and opposing lower surface 28 define alight pipe 30 therebetween. At least one of the upper surface 26 and thelower surface 28 of housing 24 may include one or more reflectiveportions 32. The one or more reflective portions 32 may be configured todirect light generated by the one or more light emitting elements 22 tothe one or more components of the display system 10 and, as will bedescribed in greater detail, redirect light reflected from reflectivepolarizer components provided in the display 10 back to the one or morecomponents of the display 10 to increase the operational efficiency andreduce power consumption of the backlight 20.

In one or more embodiments, a diffusing element 34 may be disposedproximate the upper surface 26 of the housing 24 of the backlight 20.The diffusing element 34 cooperates with the backlight to uniformlydistribute light generated by the one or more light emitting elements 22or reflected off of the one or more reflective portions disposed on thehousing of the backlight 20 to the one or more components of the display10 and reduce potential areas of brighter or dimmer lighting generatedby the backlight 20.

The display system 10 includes a first display unit 40 disposedproximate the backlight 20. The first display unit 40 may include ashutter cell or liquid crystal layer 42 disposed between asemi-transparent or transparent upper conductive layer or substrate 44and an opposing semi-transparent or transparent lower conductive layeror substrate 46. The first display unit 40 may include at least onereflective polarizer 50 cooperating with the upper substrate 44.

The liquid crystal layer 42 of the first display unit 40 may be a devicesuch as a Thin Film Transistor (TFT) liquid crystal display (LCD),otherwise referred to as the TFT display layer. Alternatively, the firstdisplay unit 40 may be formed as another form of liquid crystal celldevice configuration, such as multiplexed film compensated super twistnematic (FSTN), twisted nematic (TN), in-plane switching (IPS),multi-domain vertical alignment (MVA) or another type of liquid crystaldisplay mode that causes light polarization rotation.

The liquid crystal layer 42 of the first display unit 40 may include aplurality of pixels arranged in a row and column format on a thin filmarrangement. Each pixel is attached to a transistor. A charge is appliedto the transistor for each pixel to adjust the state of the pixelbetween an actuated and non-actuated state. The liquid crystal layer 42is pixelated such that each pixel may be dynamically configured tooptically rotate polarized light to produce a local dimming backlight atthe pixel level. It is contemplated, in one or more embodiments, thatthe first display unit 40 will be a monochrome TFT display or a displayunit having color filters removed from the display.

In general, propagating light waves generate an electric field. Theelectric field oscillates in a direction that isperpendicular/orthogonal to the light wave's direction of propagation.Light is unpolarized when the fluctuation of the electric fielddirection is random. Conversely, light may be described as polarizedwhen fluctuation of the electric field is highly structured, with laserbeams being a common example of highly-polarized light and sunlight ordiffuse overhead incandescent lighting being examples of unpolarizedlight.

In one or more embodiments, the at least one reflective polarizer 50includes a first reflective polarizer 50 and a second reflectivepolarizer 60. The first and second reflective polarizer 50, 60 may beformed as a film that is joined or coupled to the substrates 44, 46using an additive procedure such as an adhesive process, a bonding, anda lamination. When assembled, the first reflective polarizer 50, uppersubstrate 44, liquid crystal layer 42, lower substrate 46 and secondreflective polarizer 60 cooperate to form the first display unit 40.

The second reflective polarizer 60 may be configured to only allow lightdirected from the backlight 20 with the correct polarization angle topass through the second reflective polarizer 60. Conversely, lightdirected from the backlight 20 that is not of the correct polarizationangle is reflected back by the second reflective polarizer 60.

The first reflective polarizer 50 includes a body 52 having an uppersurface 54 and an opposing lower surface 56 that cooperates with theupper substrate 44 of the first display unit 40. The second reflectivepolarizer 60 includes a body 62 including an upper surface 64cooperating with the lower substrate 46 of the first display unit 40 andan opposing lower surface 66. The first reflective polarizer 50 andsecond reflective polarizer 60 may each include a reflective polarizerfilm bonded or otherwise attached to one or more surfaces of the firstreflective polarizer 50 and second reflective polarizer 60. As is shownin FIG. 3, the lower surface 66 of the second reflective polarizer 60may cooperate with a brightness enhancing film (BEF) 68 to reorient andenhance light from outer regions or angles of the backlight 20 into acentral region proximate the liquid crystal layer 42 of the firstdisplay unit 40.

Two special classes of reflective polarizer materials that may be usedfor cooperating with the first reflective polarizer 50 and secondreflective polarizer 60, or in the construction of the first reflectivepolarizer 50 and the second reflective polarizer 60, may includecommercially available as 3M™ Reflective Polarizer Mirror (RPM) and 3M™Windshield Combiner Film (WCF), both available from THE 3M COMPANY, withheadquarters located in Maplewood, Minn. Other reflective polarizermaterials having similar properties such as wire grid polarizers may beused to form the first and second reflective polarizer 50, 60 in otherembodiments.

The display system 10 additionally includes a second display unit 70disposed proximate the first display unit 40. The second display unit 70may include a TFT display layer 72 having an upper substrate 74 and anopposing lower substrate 76. The TFT display layer 72 may be configuredas a TFT display or may be formed as a device such as, a Liquid CrystalDisplay (LCD) or the like, for use as a digital presentation device todisplay content, such as a group of virtual or reconfigurableinstruments that display operational information of the vehicle.

In one or more embodiments, the TFT display layer 72 of the seconddisplay unit 70 may include a liquid crystal display disposed betweenthe upper substrate 74 and the lower substrate 76. The substrates 74, 76of the second display unit 70 may be formed from glass and provide astructure on which to apply additive materials such as a color filter,for example.

At least one linear polarizer 80 may cooperate with the TFT displaylayer 72 to form the second display unit 70. The at least one linearpolarizer 80 may be formed as a film that cooperates with one or more ofthe upper substrate 74 and the lower substrate 76 of the second displayunit 70. Linear polarizers are polarizers designed to linearly polarizeincoming light and absorb light that is not in the correct polarizationangle. Passing white light through a linear polarizer blocks half of theincident light, causing the electric field component to displace so thatit oscillates in only one plane with respect to the direction ofpropagation.

In one or more embodiments, the at least one linear polarizer 80 mayinclude a first linear polarizer 80 and a second linear polarizer 90.The first linear polarizer 80 includes a body 82 including an uppersurface 84 cooperating with the lower substrate 76 of the second displayunit 70 and an opposing lower surface 86.

The second linear polarizer 90 includes a body 92 having an uppersurface 94 and an opposing lower surface 96 cooperating with the uppersubstrate 74 of the second display unit 70. The first and second linearpolarizer 80, 90 may be joined or coupled to the TFT display 72 andsubstrates 74, 76 to form the second display unit 70 using an additiveprocedure such as an adhesive process, a bonding, and a lamination.

The first linear polarizer 80 may be configured to allow lighttransmitted from the backlight 20 to pass through to the TFT displaylayer 72. Conversely, the second linear polarizer 90 may be configuredto control the emittance of light from the TFT display layer 72. In oneor more embodiments, transmission axes of the first reflective polarizer50 and the second reflective polarizer 60 are aligned with atransmission axis of the first linear polarizer 80.

In one or more embodiments, a diffuser 100 may be provided in thedisplay 10 and disposed between at least the first display unit 40 andthe second display unit 70. In the embodiments shown in the Figures, thediffuser 100 may be disposed and positioned between the upper surface 54of the first reflective polarizer 50 and the lower surface 86 of thefirst linear polarizer 80. The diffuser 100 may provide a Gaussian likeluminance or light profile transition for light transmitted through thefirst display unit 40, such that any edges between the lit pixels of thefirst display unit 40 and unlit pixels of the first display unit 40fades gradually. Unlike a sharp luminance transition that is morenoticeable to a user, the Gaussian like luminance or light profiletransition created by the diffuser creates a more gradual fade profilethat is more difficult for the user to discern the edges between the litand unlit pixels of the first display unit 40 as the individualdynamically configured pixels either rotate or do not rotate thepolarized light to produce a local dimming backlight feature at thepixel level.

In an alternative embodiment of the display system 10 shown in FIG. 4,the first display unit 40 is positioned proximate the second displayunit 70. The second display unit 70 includes a linear polarizer 90 witha body 92 having an upper surface 94 and an opposing lower surface 96cooperating with the upper substrate 74 of the second display unit 70.The upper surface 54 of the first reflective polarizer 50 cooperateswith the lower substrate 76 of the second display layer 70 to controlthe emittance of light projected from the one or more light emittingelements 22 and backlight 20 through the first display unit 40 into theTFT display layer 72 of the second display unit 70. The first reflectivepolarizer 50 may be joined or coupled to the substrate 44 of the firstdisplay 40 and the substrate 76 of the second display unit 70 using anadditive procedure such as an adhesive process, a bonding, and alamination.

Referring now to FIG. 5, the display system 10 is shown in at least afirst configuration, wherein light is projected from the backlight 20through the one or more components of the display system 10. In thisfirst configuration, the first display unit 40 is placed in a firsttransmissive state or driven state. In the first transmissive state,polarized light, generally represented by arrow 102, is projectedthrough the first display unit 40 without adjustment or treatment by theliquid crystal layer 42 or one or more of the first reflective polarizer50 and second reflective polarizer 60.

The polarized light 102 projects through the first reflective polarizer50 to the diffuser 100, where the light is diffused and distributed in agenerally uniform fashion as represented by arrows 104 for projectionthrough the first liner polarizer 80 and TFT display layer 72. The TFTdisplay layer 72 of the second display unit 70, in response to one ormore control signals 16 from the at least one microcontroller 12 shownin FIG. 2, may render one or more display features or content resultingin an image that will be projected by the light 102 passingtherethrough.

In one or more embodiments, if all the layers or components of thedisplay system 10 are laminated together and aligned at the pixel level,local zones could be produced by the first display unit 40 that may belarger by a factor of about 2 times to about 9 times to adjust or aligntolerances, thereby reducing or providing a constrained halo zone oflight that will be difficult to see due to the luminance of the adjacenttransmitting pixel.

Referring now to FIG. 6, the display system 10 is shown in at least asecond configuration, wherein the first display unit 40 is placed in asecond transmissive state or undriven state. In the second transmissiveor undriven state, the at least one microcontroller 12 as shown in FIG.2, via one or more control signals 16, in response to one or more inputsignals 14 instructs the display system 10 to adjust the dimming levelof the display system 10.

The pixelated liquid crystal layer 42 of the first display unit 40, inresponse to the one or more control signals 16 from the at least onemicrocontroller 12 as shown in FIG. 2, is configured to rotate polarizedlight received from the backlight 20 by up to 90 degrees, as isrepresented by arrow 106. The liquid crystal layer 42 of the firstdisplay unit 40, as a pixelated TFT display, may be dynamicallyconfigured to cause individual pixels to either optically rotate or notoptically rotate the polarized light to produce a local dimmingbacklight at the pixel level. It is understood that an individual pixelmay dynamically change independently of another pixel. This dynamiccontrol produces the local dimming backlight feature at the pixel level.

In one non-limiting example, in a first transmissive state or drivenstate, about ninety percent (90%) of the polarized light 102 projectedthrough the second reflective polarizer 60 may be transmitted throughthe first reflective polarizer 50 to the second display unit 70 todisplay an image. About ten percent (10%) of the polarized lightprojected through the second reflective polarizer 60 may be reflected.

In another non-limiting example, in a second transmissive or undrivenstate, polarized light 106 is rotated up to 90 degrees by the pixelatedliquid crystal layer 42 and is reflected by the first reflectivepolarizer 50 and redirected to be rotated up to another 90 degrees orundergoes a 90-degree twist through the pixelated liquid crystal layer42. In response to the 90-degree twist of the polarized light 106through the pixelated liquid crystal layer 42, the polarized light 106is aligned to the transmission axis of the second reflective polarizer60 and is therefore transmitted back into the backlight 20 for recyclingand reuse by the display system 10. It is also understood that thepixelated liquid crystal layer 42, as illustrated in FIGS. 6 and 8, isdynamically configured to optically rotate polarized light when adjustedbetween the first transmissive state and the second transmissive stateto produce a local dimming backlight through the first display unit 40at the pixel level such that polarized light 102 projects through thefirst reflective polarizer 50 to the diffuser 100, where the light isdiffused and distributed in a generally uniform fashion as representedby arrows 104 for projection through the first liner polarizer 80 andTFT display layer 72.

In yet another non-limiting example, in a second transmissive orundriven state, about zero percent (0%) of the orthogonal polarizedlight is transmitted by the first reflective polarizer 50 to the seconddisplay unit 70 such that almost no light will pass to the seconddisplay unit 70, providing at least a contrast ratio of about 10,000:1.The light 108, whose polarization is orthogonal to the transmission axisof the second reflective polarizer 60, is reflected back into thebacklight 20 for recycling and reuse by the display system 10.

About ninety percent (90%) of the reflected light 106 will transmitthrough the second reflective polarizer 60 into the backlight 20 forreprocessing. As a result, about eighty-one percent (81%) of thereflected light will be recycled for the pixels in the undriven state ofthe first display unit 40. Since about 81% of the light is recycled forundriven pixels in the first display unit 40, a greater amount of lightwill be recycled compared to an exemplary display, wherein a linearpolarizer absorbs the light.

The at least one microcontroller 12 cooperates with the display system10 to dynamically control the backlight luminance to assure that theluminance level stays constant. The at least one microcontroller 12 maycontrol the luminance by adjusting the voltage levels supplied to theTFT cells in the liquid crystal layer 42 of the first display unit 40 tolocally dim the display system 10.

In one or more embodiments, the transmission axis of the firstreflective polarizer 50 is aligned with a transmission axis of the firstlinear polarizer 80. The transmissivity state of the display system 10may be adjusted to one or more configurations as set forth in the tablebelow and as shown in FIGS. 5, 6 and 8. Examples 1 and 2 contemplate anarrangement wherein the transmission axes of the first reflectivepolarizer 50 and second reflective polarizer 60 are aligned in parallel.Examples 3 and 4 contemplate an arrangement wherein the transmissionaxes of the first reflective polarizer 50 and second reflectivepolarizer 60 are cross aligned. The liquid crystal layer 42 of the firstdisplay unit 40 is pixelated such that each pixel may be dynamicallyconfigured to optically rotate as illustrated in FIG. 8, that is, eitherrotate or not rotate, polarized light, thereby producing a local dimmingbacklight at the pixel level:

Reflective Polarizer Transmission Axis Undriven State Polarized DrivenState Polarized Orientation Light Rotation Light Rotation Example 1 -Parallel 90°  0° Example 2 - Parallel  0° 90° Example 3 - Cross 90°  0°Example 4 - Cross  0° 90°

In one or more embodiments described herein and as set forth innon-limiting Example 1 in the table above. In Example 1, polarized lightis rotated 90 degrees when the liquid crystal layer 42 of the firstdisplay unit 40 is in an undriven state and the first reflectivepolarizer 50 and second reflective polarizer 60 are aligned in parallel.Conversely, in Example 3, polarized light is rotated 90 degrees when theliquid crystal layer 42 of the first display unit 40 is in an undrivenstate and the first reflective polarizer 50 and second reflectivepolarizer 60 are cross aligned. It is understood that, in an arrangementwhere the first reflective polarizer 50 and second reflective polarizer60 are cross aligned, the first reflective polarizer 50 and first linearpolarizer 80 are aligned in parallel.

Referring now to FIG. 7, the disclosed display system and the variousteachings set forth above may be used as part of a method of adjustinglight intensity by repurposing or recycling light using the displaysystem 10, generally referenced as 110, is described in greater detail.At block 112, the at least one microcontroller 12 in FIG. 2 receives oneor more input signals to render content in a display image on thedisplay system 10 and transmit a signal representative of at least afirst light intensity value to the one or more light emitting elementsto generate and project light at the first intensity value from thebacklight to the first display unit.

In one or more embodiments, the one or more input signals may berepresentative of values or measurements of the operating states of atleast one component of a vehicle, including, but not limited to, outputfrom the vehicle speed sensor, and the like. The at least onemicrocontroller 12 may propagate the commands and information receivedin the one or more input signals and render the content as a displayimage associated with the speed of the vehicle as a virtual speedometer.The one or more input signals may additionally include input signalsreceived from an actuating device or an ambient light sensor to generatethe display image with a lighting or contrast level, such as a contrastlevel of about seventy percent (70%) black content for the displayedimage.

At block 114, the at least one microcontroller 12 may command thepixelated liquid crystal layer 42 of the first display unit 40 to adjustbetween at least a first transmissive state and a second transmissivestate. The pixelated liquid crystal layer 42, as illustrated in FIGS. 6and 8 is dynamically configured to optically rotate polarized light whenadjusted between the first transmissive state and the secondtransmissive state to produce a local dimming backlight through thefirst display unit 40 at the pixel level. The at least onemicrocontroller 12 may command the liquid crystal layer 42 of the firstdisplay unit 40 to adjust between at least a first transmissive stateand a second transmissive state based on a variety of factors, includingthe configuration or type and quantity of components, such as the numberof reflective polarizers, diffusers and the like, provided in thedisplay system 10. For example, the adjustment command by at least onemicrocontroller 12 may be based upon a display system 10 configurationhaving a first reflective polarizer 50 cooperating with the firstdisplay unit 40.

The adjustment calculation or command may also take other factors intoconsideration, including, but not limited to, whether light entering thefirst display unit 40 is polarized and adjusting resolution of the firstdisplay unit by a factor of about nine (9) to increase the apertureratio so that the light obstruction caused by the metalized column linesand row lines of the TFT cell structure of the liquid crystal layer 42is evaluated. The factor of about nine (9) disclosed above results in acalculation that area of nine color TFT pixels on the TFT display layer72 of the second display unit 70 has a local dimming area of one TFTpixel on the liquid crystal layer 42 of the first display unit 40. Anexample of this evaluation is reproduced in the chart below:

Transmission Notes Reflective polarizer (50) 0.9 3M RPM data MonochromeTFT (42) 0.95 1-50%/9 for reduced resolution Total Transmission 0.855Does not include rear polarizer that is part of a normal backlight

At block 116, the at least one microcontroller 12 may calculate theamount of recycled or reprocessed light generated by the display system10. The amount of recycled or reprocess light may be subject to factorsincluding, but not limited to, the transmissive state of the liquidcrystal layer 42 of the first display unit 40, the number and positionof reflective polarizers 50, 60, and the like. In one non-limitingexample, the amount of light that may be recycled to the backlight 20 isabout fifty-four percent (54%). A representative calculation is shownbelow:

Notes Recycled light 0.7 70% black 30% white assumption monochrome TFTAR 0.95 AR = Aperture Ratio RPM recycle efficiency 0.81 Recycled light0.53865 54% of light is recycled

The amount of light that is recycled by the display system 10 may bedependent on the type of content to be displayed or rendered in animage. The content of the rendered image may change dynamically. Assuch, the at least one microcontroller 12 of the display systemdynamically adjusts the output of the backlight 20 in response tofeedback control from one or more components of the display system 10 orin response to calculations stored with executable instructions in theat least one microcontroller 12.

At block 118, the at least one microcontroller 12 may determine theamount of light generated by the backlight 20 relative to a backlight 20cooperating with at least one reflective polarizer 50 and transmit asignal representative of at least a second light intensity value to theone or more light emitting elements 22 to generate and project light atthe second light intensity value from the backlight 20 to the firstdisplay unit 40 to display the rendered image on the second display unit70. In one non-limiting example shown in the table below, the firstdisplay unit 40 containing the liquid crystal layer 42 and at least onereflective polarizer 50 has a transmission of about eighty-five andone-half percent (85.5%). As a result, the at least one microcontroller12 may increase, the backlight 20 light output a factor of 1.17 to makeup for the loss created by presence of the liquid crystal layer 42 andat least one reflective polarizer 50 of the first display unit 40.

Since fifty-four percent (54%) of the light is recycled by the displaysystem 10, the at least one microcontroller 12 estimates that aboutfifty percent (50%) of the recycled light returning to the backlight 20may be recycled to exit the backlight 20 in the correct polarization. Itis understood that the actual amount of light exiting the backlight 20may vary depending of the recycling efficiency of the backlightstructure. As such, the at least one microcontroller 12 can reduce thebacklight output to about seventy-three percent (73%) of the originalbacklight output, resulting in a total of about eighty-five percent(85%) of the light required compared to a conventional backlight.

Relative Amount of Backlight Light Required Notes Factor for monochrome1.16959064 =1/.855 Factor for recycling 0.73 1-.54/2 Total 0.854 Thismeans we only need 85% of the light compared to a normal backlight dueto recyclingThe resultant lower backlight output provides a more energy efficient,lower power consumption display system 10.

The foregoing detailed description and the drawings are supportive anddescriptive of the disclosure, but the scope of the disclosure isdefined solely by the claims. As will be appreciated by those ofordinary skill in the art, various alternative designs and embodimentsmay exist for practicing the disclosure defined in the appended claims.

The invention claimed is:
 1. A display system comprising: a backlightincluding a housing and one or more light emitting elements received inthe housing to generate and project light from the backlight and one ormore reflective portions disposed on the housing; a first display unitdisposed proximate the backlight, wherein the first display unitincludes an upper substrate, a liquid crystal layer cooperating with theupper substrate of the first display unit, a lower substrate disposedopposite the upper substrate of the first display unit and cooperatingwith the liquid crystal layer, and at least one reflective polarizercooperating with one or more of the upper substrate of the first displayunit and the lower substrate of the first display unit, wherein theliquid crystal layer is pixelated such that each pixel is dynamicallyconfigured to optically rotate polarized light to produce a localdimming backlight at the pixel level; a second display unit disposedproximate the first display unit, wherein the second display unitincludes an upper substrate, a thin film transistor (TFT) display layercooperating with the upper substrate of the second display unit, a lowersubstrate disposed opposite the upper substrate of the second displayunit and cooperating with the TFT display layer, and at least one linearpolarizer cooperating with one or more of the upper substrate and thelower substrate of the second display unit; and at least onemicrocontroller in communication with one or more of the backlight, thefirst display unit and the second display unit, wherein the at least onemicrocontroller is configured to execute instructions to adjust theliquid crystal layer of the first display unit between at least a firsttransmissive state and a second transmissive state, wherein polarizedlight transmitted from the backlight is projected through the liquidcrystal layer of first display unit to the second display unit and asecond transmissive state, wherein the liquid crystal layer rotates thepolarized light transmitted from the backlight up to 90 degrees.
 2. Thedisplay system of claim 1 further comprising a diffusing elementdisposed proximate an upper surface of the housing, wherein thediffusing element cooperates with the backlight to distribute lightgenerated and projected by the one or more light emitting elements orreflected from the one or more reflective portions.
 3. The displaysystem of claim 1 wherein the at least one reflective polarizer of thefirst display unit further comprises: a first reflective polarizerhaving a body including an upper surface and an opposing lower surfacethat cooperates with the upper substrate of the first display unit; anda second reflective polarizer having a body including an upper surfacecooperating with the lower substrate of the first display unit and anopposing lower surface, wherein the at least one microcontroller isconfigured to execute instructions to adjust the liquid crystal layer ofthe first display unit between at least a first transmissive state,wherein polarized light transmitted from the backlight is projectedthrough the liquid crystal layer of first display unit to the seconddisplay unit and a second transmissive state, wherein the liquid crystallayer rotates the polarized light transmitted from the backlight up to90 degrees and is reflected by the first reflective polarizer to thebacklight.
 4. The display system of claim 3 further comprising abrightness enhancing film cooperating with the lower surface of thesecond reflective polarizer.
 5. The display system of claim 1 whereinthe liquid crystal layer of the first display unit further comprises aTFT liquid crystal display (LCD) disposed between and cooperating withthe upper substrate of the first display unit and the lower substrate ofthe first display unit.
 6. The display system of claim 5 wherein theliquid crystal layer of the first display unit further comprises amonochrome TFT LCD.
 7. The display system of claim 5 wherein the liquidcrystal layer of the first display unit is pixelated, wherein each pixelis dynamically configured to optically rotate polarized light to producea local dimming backlight at a pixel level.
 8. The display system ofclaim 1 wherein the at least one linear polarizer of the second displayunit further comprises: a first linear polarizer having a body includingan upper surface cooperating with the lower substrate of the seconddisplay unit and an opposing lower surface; and a second linearpolarizer having a body including an upper surface and an opposing lowersurface cooperating with the upper substrate of the second display unit.9. The display system of claim 1 wherein the at least one linearpolarizer of the second display unit further comprises a linearpolarizer having a body including an upper surface and an opposing lowersurface cooperating with the upper substrate of the second display unit,wherein the upper surface of the first reflective polarizer cooperateswith the lower substrate of the second display unit to control lightemittance from the first display unit into the TFT display layer of thesecond display unit.
 10. The display system of claim 1 wherein the TFTdisplay layer of the second display unit further comprises a TFT LCDdisposed between and cooperating with the upper substrate of the seconddisplay unit and the lower substrate of the second display unit.
 11. Thedisplay system of claim 10 wherein the TFT display layer of the seconddisplay unit further comprises a color TFT LCD.
 12. The display systemof claim 1 further comprising a diffuser disposed between the firstdisplay unit and the second display unit, wherein the diffuser providesa light profile transition for light transmitted through the firstdisplay unit.
 13. A display system comprising: a backlight including ahousing and one or more light emitting elements received in the housingto generate and project light from the backlight and one or morereflective portions disposed on the housing; a first display unitdisposed proximate the backlight, wherein the first display unitincludes: an upper substrate, a liquid crystal layer cooperating withthe upper substrate of the first display unit, wherein the liquidcrystal layer is pixelated such that each pixel is dynamicallyconfigured to optically rotate polarized light to produce a localdimming backlight at the pixel level, a lower substrate disposedopposite the upper substrate of the first display unit and cooperatingwith the liquid crystal layer, a first reflective polarizer having abody including an upper surface and an opposing lower surface thatcooperates with the upper substrate of the first display unit, and asecond reflective polarizer having a body including an upper surfacecooperating with the lower substrate of the first display unit and anopposing lower surface; a second display unit disposed proximate thefirst display unit, wherein the second display unit includes: an uppersubstrate, a thin film transistor (TFT) display layer cooperating withthe upper substrate of the second display unit, a lower substratedisposed opposite the upper substrate of the second display unit andcooperating with the TFT display layer, a first linear polarizer havinga body including an upper surface cooperating with the lower substrateof the second display unit and an opposing lower surface; and a secondlinear polarizer having a body including an upper surface and anopposing lower surface cooperating with the upper substrate of thesecond display unit; a diffuser disposed between the first display unitand the second display unit, wherein the diffuser provides a lightprofile transition for light transmitted through the first display unit;and at least one microcontroller in communication with one or more ofthe backlight, the first display unit and the second display unit,wherein the at least one microcontroller is configured to executeinstructions to adjust the liquid crystal layer of the first displayunit between at least a first transmissive state, wherein polarizedlight transmitted from the backlight is projected through the liquidcrystal layer of first display unit to the second display unit and asecond transmissive state, wherein the liquid crystal layer rotates thepolarized light transmitted from the backlight up to 90 degrees and isreflected by the first reflective polarizer to the backlight.
 14. Thedisplay system of claim 13 further comprising a diffusing elementdisposed proximate an upper surface of the housing, wherein thediffusing element cooperates with the backlight to distribute lightgenerated and projected by the one or more light emitting elements orreflected from the one or more reflective portions.
 15. The displaysystem of claim 13 further comprising a brightness enhancing filmcooperating with the lower surface of the second reflective polarizer.16. The display system of claim 13 wherein the liquid crystal layer ofthe first display unit further comprises a monochrome TFT liquid crystaldisplay (LCD) disposed between and cooperating with the upper substrateof the first display unit and the lower substrate of the first displayunit.
 17. The display system of claim 13 wherein the liquid crystallayer of the first display unit is pixelated, wherein each pixel isdynamically configured to optically rotate polarized light to produce alocal dimming backlight at a pixel level.
 18. The display system ofclaim 13 wherein the TFT display layer of the second display unitfurther comprises a color TFT LCD disposed between and cooperating withthe upper substrate of the second display unit and the lower substrateof the second display unit.
 19. A non-transitory computer-readablemedium with computer-readable instructions stored therein for adjustinglight intensity of a display system, the display system including abacklight with one or more light emitting elements to generate andproject light, a first display unit disposed proximate the backlightincluding at least one reflective polarizer and a second display unitproximate the first display unit configured to render an image, whereinexecution of the computer-readable instructions by a processor of amicrocontroller causes the microcontroller to: transmit a signalrepresentative of at least a first light intensity value to the one ormore light emitting elements to generate and project light at the firstlight intensity value from the backlight to the first display unit;command a pixelated liquid crystal layer of the first display unit toadjust between at least a first transmissive state and a secondtransmissive state, wherein the pixelated liquid crystal layer isdynamically configured to optically rotate polarized light when adjustedbetween the first transmissive state and the second transmissive stateto produce a local dimming backlight through the first display unit at apixel level; calculate an amount of light recycled by the at least onereflective polarizer of the first display unit to the backlight; andtransmit a signal representative of at least a second light intensityvalue to the one or more light emitting elements to generate and projectlight at the second light intensity value from the backlight to thefirst display unit to display the rendered image on the second displayunit.
 20. The computer-readable medium of claim 19, wherein execution ofthe computer-readable instructions by the processor of themicrocontroller causes the microcontroller to: receive one or more inputsignals from one or more components to render content of the image inresponse to the one or more input signals; and command projection of theimage by a TFT display layer of the second display unit.